Incorporated herein by this reference is Spanish Application No. 9602302, filed on Oct. 30, 1996. This U.S. application claims priority under 35 U.S.C. 119 to Spanish Application No. 9602302, filed on Oct. 30, 1996.
The present invention relates to new organometallic catalysts to the process for preparation thereof and their use for the polymerization and copolymerization of ethylene and alpha-olefins in industrial production plants.
There is a great variety of processes and catalysts useful for the homo- and copolymerization of olefins. Catalytic systems such as Ziegler-Natta are typically able to produce polyolefins with high molecular weight and broad distribution of molecular weight. However, for many industrial applications it is of the greatest importance to obtain polyolefins characterized by a high molecular weight, and narrow molecular weight distribution. Besides, with these Ziegler-Natta type of catalysts, to obtain copolymers with fit comonomer contents it is necessary to use high comonomer/monomer molar ratios in the feed and as a consequence the industrial process becomes enormously more expensive.
In the last years there has been the development of organometallic catalytic metallocene systems, that, combined with non-coordinative anions, alkylaluminoxanes or boron perfluorinated compounds (U.S. Pat. No. 4,542,199 and EP 426637) allow to obtain polyolefins with narrow distributions of molecular weight and high molar comonomer contents. However, the molecular weights are not as high as it would be useful to give the polymer the desired properties. Besides, these molecular weights suddenly lower when the comonomer content increases, or when the polyme zation temperature rises.
In EP 416815 and EP 420436 there is the description of a new type of organometallic catalysts in which a transition metal is coordinated to a cyclopentadienyl ring and to a heteroatom. These organometallic compounds, when they are activated with alkylaluminoxanes, are able to produce ethylene polymers with high molecular weight and narrow distribution of molecular weight. They moreover own a great effectiveness in comonomer incorporation. However, when the comonomer content of the polymeric chain is increasing, the molecular weight sensibly decreases.
Therefore it is an object of the present invention to provide new compounds, useful in the (co)polymerization of alpha-olefins, in particular in the (co)polymerization of ethylene, which can produce polymers with high molecular weights. Besides, these catalysts are especially efficient in the comonomer incorporation, and produce copolymers with totally random distributions of the comonomer.
The organo metallic complexes (catalysts) disclosed in the present invention are characterized by the following general formula I: 
wherein:
M is a transition metal of groups 3, 4-10 of the periodic table of the elements, lanthanide or actinide, preferably titanium, zirconium or hafnium.
Each X group, equal to or different from each other, is hydrogen, halogen, alkyl, cycloalkyl, aryl, alkenyl, arylalkyl, arylalkenyl or alkylaryl with 1 to 20 carbon atoms, linear or branched, the hydrogens of these groups optionally are substituted by SiR3, GeR3, OR, NR2, OSiR3 groups or any combination thereof wherein R is selected from the group comprising: hydrogen, C1-C20 alkyl, C3-C20 cycloalkyl, C6-C20 aryl, C7-C20 alkenyl, C7-C20 arylalkyl, C7-C20 arylalkenyl or alkylaryl, branched or linear.
n is a number whose value is: 0, 1, 2 or 3, in order to fill the remaining free valences of the metal M;
L is a neutral Lewis base such as dietylether, tetrahydrofurane, dimethylaniline, aniline, triphenilphosphine, n-butylamine, etc.
z is a number whose value is: 0, 1, 2 or 3.
A is a ring with delocalized xcfx80 electrons, that directly coordinates to the transition metal M. Preferably A is a cyclopentadienyl type of ring of formula C5R14, wherein each RW group, equal to or different from each other is hydrogen, C1-C20 alkyl, C3-C20 cycloalkyl, C6-C20 aryl, C7-C20 alkenyl, C7-C20 arylalkyl, C7-C20 arylalkenyl or alkylaryl, branched or linear, the hydrogens of these groups optionally are substituted by SiR3, GeR3, OR, NR2, OSiR3 groups or any combination thereof wherein R is above defined; R1 is also selected from the group comprising SiR3, GeR3, OR, R2N, OSiR3 groups or any combination thereof. Two adjacent R1 optionally unite in order to form a saturated or unsaturated polycyclic cyclopentadienyl ring such as indenyl, tetrahydroindenyl, fluorenyl or octahydrofluorenyl, optionally substituted with R1 groups.
RII is hydrogen, alkyl, cycloalkyl, aryl, alkenyl, arylalkyl, arylalkenyl or alkylaryl from 1 to 20 carbon atoms, linear or branched, whose hydrogens are optionally substituted by SiR3, GeR3, OR, NR2, OSiR3 groups or any combination thereof wherein R is above defined; it optionally forms a condensed ring through another bond with E. Preferably RII is tertbutyl.
Each E group, equal to or different from each other, is BRIII, CRIV2, SiRIII2, GeRIII2; at least one E is SiRIII2. Preferably the bridge Exe2x80x94E is CRIV2xe2x80x94SiRIII2. Each RIII, equal to or different from each other, is hydrogen, alkyl, cycloalkyl, aryl, alkenyl, arylalkyl, arylalkenyl or alkylaryl with 1 to 20 carbon atoms, linear or branched, whose hydrogens optionally are substituted by SiR3, GeR3, OR, NR2, OSiR3 groups or any combination thereof wherein R is above defined; RIV has the same meaning of RIII or it is halogen; besides two groups selected from RIV and RIII belonging to different E optionally form a cyclic structure.
The catalysts component of general formula I, can be suitably prepared through reaction of a compound of general formula Mxe2x80x2xe2x80x94Axe2x80x94Exe2x80x94Exe2x80x94NRIIxe2x80x94Mxe2x80x2, wherein Mxe2x80x2 is Li, Na or K, with a metal M compound, preferably of formula MX4 or with an adduct of formula MX42L or MX33L, where X is above defined and L preferably is a linear or cyclic ether as for example: ethylic ether, tetrahydrofurane, dimetoxyethane, etc. 
The compound of general formula Mxe2x80x2xe2x80x94Axe2x80x94Exe2x80x94Exe2x80x94NRIIxe2x80x94Mxe2x80x2 can be suitably prepared through reaction of HAxe2x80x94Exe2x80x94Exe2x80x94NRIIH with two equivalents of an alkyl or aryl alkali metal salt, or with an alkali metal hydride or an alkaline metal: 
Wherein Rc is C1-C20 alkyl or C6-C20 aryl.
Alternatively, alkyl magnesium salts, which are obtained in the same way, can be used, but using an alkyl magnesium halide instead of alkyl lithium.
When the bridge Exe2x80x94E is SiRIII2xe2x80x94CRIV2, the compound HAxe2x80x94SiRIII2xe2x80x94CRIV2xe2x80x94NRIIH can be suitably prepared starting from a compound of general formula HAxe2x80x94SiRIII2xe2x80x94CRIV2xe2x80x94OH or its lithium salts. The process comprises the following steps:
a) reacting a compound of formula HAxe2x80x94SiRIII2xe2x80x94CRIV2xe2x80x94OJ wherein J is lithium or hydrogen with an alkyl- or aryl-sulphonates according to the scheme:
HAxe2x80x94SiRIII2xe2x80x94CRIV2xe2x80x94OJ+ClSO2Raxe2x86x92HAxe2x80x94SiRIII2xe2x80x94CRIV2xe2x80x94OSO2Ra
b) contacting the recovered product of step a) with an excess of an amine of formula NRIIH2
HAxe2x80x94SiRIII2xe2x80x94CRIV2xe2x80x94OSO2Ra+H2NRIIxe2x86x92HAxe2x80x94SiRIII2xe2x80x94CRIV2xe2x80x94NHRII+HNRIIxe2x80x94OSO2Ra
wherein Ra is C1-C20 alkyl, perfluoroalkyl or C6-C20 aryl radical.
During the process for obtaining the intermediate compound of formula HAxe2x80x94Exe2x80x94Exe2x80x94NRIIH and their alkali metal or magnesium halide salts, as well as the organometallic complexes obtained therefrom with the transition metal salts, the reaction temperature is kept between xe2x88x92100xc2x0 C. and 95xc2x0 C., preferably between xe2x88x9280xc2x0 C. and 80xc2x0 C., operating preferably under nitrogen inert atmosphere.
As non polar solvents pentane, hexane and toluene can be used; as polar aprotic solvents ethers such as diethyl ether, tetrahydrofurane or dimetoxyethane can be used.
During the whole process, both the chemical species and the solvents were protected from oxygen and humidity. The organometallic catalysts, when stored under inert atmosphere, are active in polymerization for long periods of time.
Non-limiting examples of compounds of general formula I are:
(1-tertbutylamide-2-cyclopentadienyl-1,1-dimethylsilaethanediyl)titanium dichloride
(1-tertbutylamide-2-cyclopentadienyl-1,1-dimethylsilaethanediyl))zirconium dichloride
(1-tertbutylamide-2-cyclopentadienyl-1,1-dimethylsilaethanediyl)hafnium dichloride
(1-tertbutylamide-1,1-dimethylsilaethanediyl-2-(tetramethylcyclopentadienyl)titanium dichloride
(1-tertbutylamide-1,1-dimethylsilaethanediyl-2-(tetramethylcyclopentadienyl)zirconium dichloride
(1-tertbutylamide-2-(tetramethylcyclopentadienyl)-1,1,2,2-tetramethyldisilanediyl)titanium dichloride
(1-tertbutylamide-2-(tetramethylcyclopentadienyl)-1,1,2,2-tetramethyldisilanediyl)zirconium dichloride
(1-teributylamide-2-(1-indenyl)-1,1-dimethylsilaethanediyl)titanium dichloride
(1-tertbutylamide-2-(1-indenyl)-1,1-dimethylsilaethanediyl)zirconium dichloride
(1-tertbutylamide-2-(1-indenyl)-1,1-dimethylsilaethanedlyl)hafnium dichloride
(1-tertbutylamide-2-(1-indenyl)-1,1,2,2-tmethylsilaethanediyl)titanium dichloride
(1-tertbutylamide-2-(1-indenyl)-1,1,2,2-tetrametylsilaethanediyl)zirconium dichloride
(1-tertbutylamide-2-(1-(2methylindenyl)-1,1-dimethylsilaethanediyl)titanium dichloride
(1-tertbutylamide-2-(1-(2methylindenyl)-1,1-dimethylsilaethanediyl)zirconium dichloride
(1-tertbutylamide 2-(9-fluorenyl) 1,1)-dimethylsilaethanediyl)titanium dichloride
(1-tertbutylamide 2-(9-fluorenyl) 1,1-dimethylsilaethanediyl)zirconium dichloride
The organometallic catalysts of formula I can be used in the polymerization and copolymerization of alpha-olefins through the addition of cocatalysts. These cocatalysts are compounds which can form non-coordinative anions, such as alkylaluminoxanes or boron perfluorinated compounds. Representative, but non-limiting, examples are methylaluminoxane, ethylaluminoxane, dimethylanilinotetrakys(pentafluorophenyl)borane, and trispentafluorophenylborane. In case boron derivatives are used, it is preferable to add to the polymerization medium little quantities of aluminium alkyls (TIBA, TEA, TMA, etc.).
The catalytic systems thus prepared are fit for the polymerization of alpha-olefins with 2 to 20 carbon atoms, in particular for the polymerization of ethylene, and for the copolymerization of ethylene with at least one alpha-olefin with 3 to 20 carbon atoms, such as propylene, 1-butene, 4-methyl-pentene, 1-hexene, etc. with dienes, with cycloalkenes and with styrene. The polymerization can be realized through a process in solution, in suspension, in gas phase or in bulk at high pressure and temperature. When using a process in suspension, hydrocarbon solvents, such as branched or linear aliphatic hydrocarbons (hexane, heptane, isobutane, etc.), cyclic hydrocarbons (benzene, toluene, xylene, etc.) or a mixture thereof are used as reaction medium. The polymerization can be realized between 1 and 4000 atmospheres and temperatures between xe2x88x9260 and 300xc2x0 C., preferably between 40 and 220xc2x0 C., and the polymerization time can vary between 20 seconds and 6 hours, according to the process.
The used concentration of the organometallic catalyst, is from 10xe2x88x927 to 10xe2x88x923 M, preferably form 10xe2x88x926 to 10xe2x88x924 M. The organoaluminum compound (for example an alumininoxane) is used in a concentration from 10xe2x88x924 to 10xe2x88x921 M, preferably from 10xe2x88x923 to 102 M. However, bigger concentrations of both components are possible as well. When an aluminoxane is used as a cocatalyst, the used Al/M molar ratio ranges from 100 to 10000, preferably between 500 and 1500. When a boron compound is used, the molar ratio varies in the range 0.5-10, preferably between 0.9-5.
The molecular weight of the obtained polymers can be controlled by varying the concentration of catalyst, cocatalyst and monomer in the polymerization medium, by varying the polymerization temperature as well as by the addition of regulators of the molecular weight such as H2. When in the preparation of the catalyst only one type of cocatalyst is used, polymers with narrow distributions of the molecular weight are obtained. However, when several types of catalysts and/or cocatalysts are used, the obtained polymers have broad distribution of molecular weight, including also multimodal distributions.
The copolymerization reactions can be realized by using the same process as the one used in the homopolymerization process, but moreover by feeding the reaction medium with the suitable comonomer or comonomers. The preferred comonomer/monomer molar ratio is comprised between 0.1/1 and 5/1. In this way, copolymers with controlled content and random distribution of comonomer are obtained.
FIG. 1 shows some examples of compounds of formula I.
The following examples are described in order to better understand the invention. The materials, the chemical compounds and the conditions used in these examples are illustrative and do not limit the scope of the invention.
The average molecular weights in number, weight and distribution were determined through gel permeation chromatography GPC or SEC. The intrinsic viscosities [xcex7] were obtained at 145xc2x0 C. through viscosimetric techniques, using as a solvent trichlorobenzene with 0.05% of antioxidant in order to prevent polymer degradation.